This is topic A/C Not Working Properly Help in forum Tech Talk at Northern California Ford Owners .
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Posted by FivePTSlow (Member # 7682) on
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I have a 1993 Mustang 5.0. I bought a nitrile o-ring replacemet kit for it and replaced all o-rings, and springs etc. I then went to charge the system and see if it worked, but it didnt. I vacuumed down the system and filled it up properly and it has the correct amount of refrigerant. I replaced the pressure switch on the top of the accumulator... nothing. I replaced the Relay under the hood that is over by the intake/maf tube and still nothing. Then I put a jumper wire across the relay receptacle and like magic the clutch kicked on and the a/c now works pretty good. The clutch cycles on and off like it's supposed to and the a/c kicks off when I hit the throttle like it's supposed to, so it appears that almost everything works like it should.
I also noticed that if I have the A/C on and the relay plugged in and I unplug the Low Pressure Switch then plug it back in the A/C clutch kicks on for a second or two then shuts off.
Any ideas what needs to be replaced, so that I don't have to run a jumper wire? I took the new relay off and put it on the fuel pump relay receptacle and the relay works fine. Is the A/C Relay different from the Fuel Pump Relay?
[ August 20, 2011, 01:39 PM: Message edited by: FivePTSlow ]
Posted by OneFastNotch. (Member # 9537) on
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pump
Posted by FivePTSlow (Member # 7682) on
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quote:
Originally posted by OneFastNotch.:
pump
Do you say this from having the same experience?
Posted by x42bnx (Member # 9529) on
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Not sure why it was running when you were trying to fill it. But, reach to the front of the compressor and see if you can spin the clutch with your hand. It should have some resistance, don't spin the pulley itself the clutch is in the middle of that.
Posted by OneFastNotch. (Member # 9537) on
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my friend did. and he just bypassed the ac and said fuck it lmao
Posted by FivePTSlow (Member # 7682) on
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quote:
Originally posted by x42bnx:
Not sure why it was running when you were trying to fill it. But, reach to the front of the compressor and see if you can spin the clutch with your hand. It should have some resistance, don't spin the pulley itself the clutch is in the middle of that.
The instructions say to have the car running with max a/c on. I've always done it this way.
I will pull off my belt and see if I can spin the clutch.
Thanks for your input
Posted by Blind (Member # 3052) on
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if the a/c is out of pressure, the controller wont' let the pump engage if the pressure is below a threshold, so you'll need to manually jump the pump to get the clutch to engage in order to charge it.
there's probably guides about this if you do a google / youtube search.
Posted by GTCONV86 (Member # 5385) on
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DID YOU VACUUM DOWN THE A/C SYS? YOU MIGHT HAVE A LOTT OF AIR IN THERE.ALSO MIGHT NEED TO JUMP THE COMPRESSOR.
Posted by FivePTSlow (Member # 7682) on
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quote:
Originally posted by GTCONV86:
DID YOU VACUUM DOWN THE A/C SYS? YOU MIGHT HAVE A LOTT OF AIR IN THERE.ALSO MIGHT NEED TO JUMP THE COMPRESSOR.
When I bought the car the line that goes to the compressor, over the manifold to the accumulator was not connected, so I know there wasn't any other refridgerants in there. It does get some pressure to the high side when I try filling it.
Posted by FivePTSlow (Member # 7682) on
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Yes I can manually turn the clutch portion with a little resistance
Posted by FivePTSlow (Member # 7682) on
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btt progress updated
Posted by Secnd2nun64 (Member # 1431) on
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Sounds like your systems low pressur switch is trying to keep you from blowing a line. Did you hook a vacuum pump up before adding refrigerant? You want to pump the system down for 20 mins, shut the pump off, close the lines and watch your gauges for another 20 mins to make sure it's holding the vacuum. If it checks out good, then you add an oil charge and a couple cans of freon to get some charge in the system. Then top off with the vehicle running.
Posted by FivePTSlow (Member # 7682) on
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I went and bought an a/c pressure switch today. I'm going to have the system evacuated again, replace the switch, vacuum the system, then add refrigerant. Hope it all goes well this time. Refrigerant is expensive!
Posted by FivePTSlow (Member # 7682) on
:
quote:
Originally posted by Secnd2nun64:
Sounds like your systems low pressur switch is trying to keep you from blowing a line. Did you hook a vacuum pump up before adding refrigerant? You want to pump the system down for 20 mins, shut the pump off, close the lines and watch your gauges for another 20 mins to make sure it's holding the vacuum. If it checks out good, then you add an oil charge and a couple cans of freon to get some charge in the system. Then top off with the vehicle running.
Last night I took it to my buddies shop where they have a nice refrigerant machine. We vacuumed the system out and replaced the refrigerant to the proper amount and pressure levels. Still cannot figure out why the a/c won't work with the relay, but will work with a jumper wire. Is there a fuse somewhere that would give the a/c relay power, or is the a/c relay different from the fuel pump relay? they have different receptacle connectors, but the pins appear to go the same direction.
Posted by 93 twintrbo (Member # 10475) on
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I would need to look up the wiring diagram for the a/c system but the relay should get a ground signal from the HVAC control head to the relay to energize the relay. Check and make sure you have the signal from the a/c request to the relay and B+ power on the switched side and also on the power side of the relay. Most likely you either have no signal from the hvac control head or possibly a bad low pressure switch if that circuit goes through it.
I am possibly confusing you, but 99% of a/c systems are very easy to diagnose and or repair. If you were close to santa Rosa or willing to travel, I am willing to help you out.
Lawrence
Posted by FivePTSlow (Member # 7682) on
:
quote:
Originally posted by 93 twintrbo:
I would need to look up the wiring diagram for the a/c system but the relay should get a ground signal from the HVAC control head to the relay to energize the relay. Check and make sure you have the signal from the a/c request to the relay and B+ power on the switched side and also on the power side of the relay. Most likely you either have no signal from the hvac control head or possibly a bad low pressure switch if that circuit goes through it.
I am possibly confusing you, but 99% of a/c systems are very easy to diagnose and or repair. If you were close to santa Rosa or willing to travel, I am willing to help you out.
Lawrence
The low pressure switch I replaced with a brand new one just a couple days ago. I thought it was more than likely that, but it does the exact same thing as before it was replaced.
I'll have to take out my multi meter and do some searching to see where I'm losing power. Everything works fine as is nad likely would work perfectly like it is for a long time, but I don't like having to make stuff work improperly.
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